Traps are branch pipes on pipelines which are used to introduce self-propelled devices known as “pigs” that advance inside the pipeline to perform cleaning and inspection operations and are recovered at the outlet after travelling through the pipeline.
The hatch according to the invention comprises an annular supporting structure designed to be welded or connected to one end of the branch pipe, a closing hatch mounted on said annular support, and means that lock the hatch in the closing position constituted by a collapsible ring, designed to fit into an annular cavity in said support in order to lock the hatch in the closing position, wherein the inside edge of said hatch is tapered to form an inclined wall designed to couple to a corresponding inclined wall in said annular support.
These characteristics enable the hatch to be opened and closed simply by rotating it around a hinge, with no need for a combined movement consisting of a traverse along the axis followed by rotation, as in other known systems.
Self-propelled devices called “pigs” are used for the purpose of inspection, control and cleaning of large pipes such as gas pipelines.
Said pigs are inserted into the pipelines and travel along them, sometimes for miles, performing a series of operations ranging from photographing the interior of the pipeline and storing the images to inspections designed to check for corroded parts or cracks in the pipeline, and cleaning of its inner surface.
Said devices, which have a diameter of several tens of centimeters, depending on the inner diameter of the pipe, and a length of up to 2-3 meters. are introduced into the pipes and travel along them, sometimes for miles, before being recovered through branch pipes.